Analysis and Control of Solid Particle Pollution in Hydraulic System of Construction Machinery WANG Hao, CHEN Guo-ping. It has important practical significance for improving the reliability of construction machinery and prolonging its service life.
According to the reliability and service life of construction machinery and hydraulic system data, about 70 of hydraulic system failures are caused by the pollution of the hydraulic system, and the 607 hydraulic pressure caused by the failure of the hydraulic system caused by the solid particle contamination accounts for the total pollution. System pollution directly affects the quality of the entire hydraulic system. Before the blood pressure of the hydraulic system is required to be printed, the system effectively reduces and controls the staining of the system. To ensure the reliability and service life of various hydraulic components and the entire system. Therefore, the rational analysis and effective control of the pollution of the hydraulic system is the key to ensure the normal and reliable operation of the hydraulic system of the construction machinery and prolong its service life.
1 Sources of hydraulic system pollutants The sources of pollution in the hydraulic system are mainly potential pollutants, regenerated pollutants and leaching pollutants. The types of pollutants in the hydraulic system can be roughly divided into solid particles, air water chemicals and micro-organisms, etc. The heart, called the body particle decay caused by 1 said to be large, 2 the hazards of solid particle pollution and the causes of the various types of pollution Among them, solid particles are the most common and hazardous pollutants in hydraulic systems. In the failure caused by the hydraulic system pollution, 20. The source is in the order, and the mechanical wear of 5, 1 is caused by the damage of one surface of the component caused by the price 1 of Sakamoto particles. 2.1 The composition and distribution of solid particles The solid particles are mainly composed of dust-borne abrasive powder deposits and fibers, etc., brought about by exfoliating colloidal metal powder air.
It deviates from the hydraulic system.樘, 2.2 The main source of solid particles The major source of solid contaminants is the following: flaky rust attached to the inner wall of a rigid pipe. Pickling 6 chemicals that remain in the pipe; 2 Iron chips 3 seals that remain in the hard pipe during processing such as cutting and threading.
Sealing ring residue. Due to the limitations of the sharp edges and dimensional pre-tightening of the joint part, the seal part may be damaged, and the damage part may directly enter the system; 4 the internal dust of the high-pressure hose assembly and some glue debris in the joint part; 5 hydraulic system assembly site Environmental factors Into the pipe inside the stone dust, etc., this situation is not much; 6 hydraulic components retained in the sand residue processing iron chips seal residual solid impurities components and oil exfoliate colloidal metal powder in the air with sand dust grinding powder deposition Material fiber fuel tank pump relief valve control valve slave cylinder hard and soft pipelines and fittings oil filter accumulator 1 of which can be; 2 medium; 3 severe test, so this is not much.
2.3 Hazard of solid particle contamination 2.3.1 Sticking and plugging of filter holes and various clearance channels makes the hydraulic pump difficult to operate and produces cavitation and noise.
2.3.2 Damage to the lubricating film increases the friction and wear of the machine.
Solid particles will cause the lubricant with a thickness less than 0.6 times the size of the solid particles to be destroyed and fire. As a result, the friction and wear of the machine are significantly increased. Wear There is a form of wear Abrasive wear Erosion wear Adhesion wear Fatigue wear and corrosion wear. The most important of these is abrasive wear. Each of these wears will create new wear, which will increase the wear of the components. Wear can lead to leakage of hydraulic components, reduced efficiency, shortened service life, and even damage.
2.3.3 Accelerate the wear of sealing materials and increase the amount of leakage. Solid particles will accelerate the damage to the hydraulic cylinder seal and cause the hydraulic cylinder to wear and wear. Causes the inside and outside of the hydraulic cylinder to increase the lack of thrust or action instability, crawling, speed, resulting in abnormal sound and vibration 2.3.4 partially or completely plug the pores of the hydraulic components, the control element lost 2.3.5 motion, the particles in the metal and The wide range of metal compounds will oxidize the oil and catalyze the oxidation of the star oil, which will catalyze the degradation of the oil quality and reduce the lubrication performance.
When the gap between components is blocked by solid particles, it will produce wear slag 99. The wear and tear of pollutants + can reach effective control. Makes system components wear out. Produce more solid particles. As a result, progress can affect the components of the entire hydraulic system. Therefore, it is necessary to remove oil contamination, especially pollutants, and ensure the normal operation of the hydraulic system.
3 Prevention and control measures Pollution control of hydraulic systems. Throughout the hydraulic system design, manufacturing. Assembling processes such as secondary use and maintenance, it is impossible to completely remove pollutants by solving the pollution of the hydraulic system, but to meet the measures of pollution and screwing, so that the degree of pollution of the system is kept within the pollution tolerance range of the hydraulic key components of the system. In order to achieve a reasonable balance, there are mainly two measures to control the pollution of the hydraulic system. 1 Prevent pollutants from intruding into the system. Filter and purify the oil in the system. 3.1 Pollution in the design stage. During the design stage, it should be carefully selected to easily generate particulate impurities. The device structure that contaminated the system oil, etc. Such as from the control of solid particles pollution point of view. Person who choose flange connection structure and use less pipe joints. Because the assembly and maintenance of the pipe joints produce a lot of wear debris; fuel tank breathing port design position higher, and try to cover some to prevent the intrusion of rain and dust; hose can be used to line the tubing and so on.
The most important design stage is the design and selection of the oil filter.
Let 10 be considered that an oil filter may be provided at the oil inlet of a hydraulic element that is sensitive to the contamination of hydraulic oil, and the oil filter may be added to the oil return point of the liquid helium element that easily generates grinded milk. Auxiliary oil filter is provided at the oil inlet of the hydraulic element. Contaminant-free systems install by-pass filtration as a supplement to on-line oil filters, improving cleanliness, prolonging filter life, and more.
3.2 Pollution in the manufacturing phase, the outsourcing purchased parts such as various valves, high pressure hoses, cylinders, etc. and hydraulic oil must be strictly tested in the factory. Keys must be loaded, run-in, and cleaned. Excluding purchased hydraulic components and some hoses, hydraulic pipes prepared on site must be rust-removed. The following processes are used for degreasing, pickling, and passivating drying and oil sealing. Before the acid washing, the pipe and the purified water under the degreasing section should be flushed with the alkaline solution on the inner and outer walls of the pipe to remove oil stains. All sealing surfaces, threads, etc. must be coated with a canopy 1 to be cleaned and pickled. The pipeline must be pressure flushed. Pressure flushing is a very important part of the hydraulic system assembly process. After the pipeline is pressurized and flushed, impurities in the pipeline can be washed away. When flushing, the key points of the welding flange flange and the elbow part are evenly tapped, so that the impurities in these parts can be shaken off with the oil.
It should be noted that the pickling and pressure flushing of pipes should be carried out on the eve of assembly, because these treatments are carried out too early and are not used for a long period of time, and there is still the possibility of rusting during pipe assembly.
Before assembly, all hydraulic components and accessories that need to be cleaned must be cleaned and closed with a sealing plug. When assembling, first of all prevent environmental pollution. Conditions can make the pressure in the chamber higher than that of the outside and prevent dust from being deposited in the atmosphere. (1) The dry assembly, ie the cleaning of the components, is dried with dry compressed air and assembled. Finally, the assembler should keep the assembly tool screens and refueling containers clean, and rigorously follow the relevant operating procedures to minimize the human-induced dyeing.
3.3 Pollution control during use and maintenance In the course of use, the hydraulic system should be inspected and maintained before and after each day's work, and all kinds of failures of the hydraulic system should be eliminated in time to prevent the disease operation 1 for a period of time, to cope with the system entering the hall, and to maintain and Maintenance, such as cleaning or replacing dirty oil filters, replacing contaminated or deteriorating hydraulic oil, etc. When replacing the hydraulic oil, the oil in the crucible box should be drained, and the clean sediment should be cleaned. Finally, the bottom of the oil tank should be flushed with proper amount of oil to be washed. The newly added oil should be the same grade as the original hydraulic oil and subjected to adequate precipitation and filtration. , And refuel with fine refueling vehicles.
During the maintenance process, it is very easy to cause pollution. Therefore, the maintenance site should be clean, and the processing residues on the newly replaced parts should be carefully cleaned. The components to be disassembled should also be cleaned and blown dry with compressed air, and be careful to block the orifices with plastic plugs or adhesive tapes. In order to prevent external pollutants Jun, 1 Lin Jizhuo, hydraulic oil overview, the Coal Industry Press 2 pollution control and filtration principles. The author of Pall Filter Co., Ltd. Wang Xiaonan, School of Mechanical and Electrical Engineering, China University of Mining & Technology, 221008
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